The functions of the Cryopreservation and Embryo Derivation Core are: A) to expeditiously transfer mutant[unreadable] mice created by the Osaka group in Japan to the La Jolla group. B) to rederive frozen embryos shipped from La[unreadable] Jolla to Osaka. C) to generate ES cell-derived chimeric mice for the establishment of knockout mice by[unreadable] microinjection of ES cells into mouse blastocysts and implantation. D) to submit mutant mouse strains to the[unreadable] MMRRC for distribution to the scientific community. Generation of mouse models have made major[unreadable] contributions to recent advances in the field of innate immunity. In the proposed project to investigate anti-viral[unreadable] immune responses by both forward and reverse genetics, close collaboration between the La Jolla group[unreadable] (conducting mouse forward genetics) and the Osaka group (conducting mouse reverse genetics) will be[unreadable] essential for success. We will exchange mutant mice and will study them in parallel using different viruses. We[unreadable] will also analyze signaling pathways based on the outcome of experiments in which ENU-induced mutations[unreadable] and knockout mutations are combined. A rapid and safe means of exchange, circumventing quarantine and[unreadable] allowing quick assessments, will be provided by this Core. The Core will also be responsible for the[unreadable] microinjection of ES cells into mouse blastocysts and re-derivation from the embryos for generating knockout[unreadable] mice. Finally, the Core will also send mutant mouse strains generated in Osaka to the MMRRC for distribution[unreadable] to the scientific community, permitting accelerated research in many laboratories worldwide.